1. Field of the Invention
The present invention relates to a gate driver for driving the gate of a semiconductor switching element of SiC, GaN, or the like.
2. Description of Related Art
FIG. 1 is a circuit diagram illustrating a gate driver according to a related art. The gate driver drives the gate of a switching element Q1 of a FET. The gate driver includes a pulse transformer T1 having a primary winding P1 and a secondary winding S1. The primary and secondary windings P1 and S1 have a turn ratio of 1:1.
In FIG. 1, both ends of a DC power source Vcc1 are connected to an npn-type transistor Q2 and a pnp-type transistor Q3. The transistors Q2 and Q3 are connected to each other in a totem-pole configuration. Bases of the transistors Q2 and Q3 receive a pulse signal Vin through a resistor R1 and emitters thereof are connected through a capacitor C1 to a first end of the primary winding P1 of the transformer T1. A second end of the primary winding P1 is connected to a collector of the transistor Q3 and a negative electrode of the DC power source Vcc1.
A first end of the secondary winding S1 of the transformer T1 is connected through a resistor R2 to the gate of the switching element Q1 and a second end of the secondary winding S1 is connected to a source of the switching element Q1.
When the pulse signal Vin has an ON duty of 50% or lower as illustrated in FIG. 2A, a peak value of a gate voltage of the switching element Q1 becomes equal to or higher than a gate-source threshold of the switching element Q1, and therefore, the switching element Q1 is driven.
Another related art is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2001-345194.